BOGOR, Indonesia — Few words are as evocative as “rainforest” — wild, mysterious, valuable beyond price and worthy of the rallying cries to save it.

Considerably less common is the expression, “Save the tropical dry forest!”

Pity the tropical dry forest. These forests — so-called because of their long dry periods — make up nearly half the world’s tropical forests and support people and iconic wildlife, just as their humid counterparts do. But they have yet to capture the attention of the public or policymakers as the world’s rainforests have, putting them at risk of mismanagement and overexploitation.

A new report could help to change that, laying out what is and is not known about tropical dry forests, and prescribing further research about an ecosystem for which a widely agreed-upon definition does not even exist.

On one issue, there is little debate: Tropical dry forests offer a crucial lifeline for hundreds of millions of rural people around the world, supplying foods and livelihoods, said Phosiso Sola, a senior scientist at the Center for International Forestry Research (CIFOR) and co-author of the report.

“Destroy these forests,” she said, “and you destroy the people’s well-being.”

Despite their importance, tropical dry forests are among the most threatened and least studied of the world’s forested ecosystems, the report states; as such, these areas may be at even greater risk of deforestation and degradation than humid forests. A lack of site-specific data, the report continues, means that the information needed to make evidence-based policy to support conservation of dry forests is “absent or incomplete.”

Small wonder, then, that these ecosystems are largely off policymakers’ radar.

What we know

The new report illuminates the contributions that dry forests make to people and landscapes in Africa, Asia and Latin America: improving food security; mitigating climate change; providing cooking fuel; bolstering health and nutrition; and supporting local agriculture by delivering a range of ecosystem services.

Sola says dry forests are especially important for rural people, many of whom supplement their meager diets and subsistence-level livelihoods by gathering wild plants, nuts, insects, mushrooms and other foods from dry forests, along with other non-wood products.

In Africa alone, Sola said, millions of people rely on dry forests not just for forest foods, but also for other valuable products like medicinal herbs, fiber, firewood, grass for thatch and brooms. “Their use as a safety net spikes dramatically during floods, drought or civil unrest,” she said.

Tropical dry forests also provide numerous benefits to smallholder farmers and pastoralists in the form of ecosystem services, such as groundwater regulation, erosion control, soil nutrient recycling and fodder for livestock.

Toby Pennington, Head of the Tropical Diversity Section at the Royal Botanic Garden in Edinburgh, Scotland, estimates that up to a billion people around the world derive their livelihoods from closed-canopy forests and tropical savanna, the two principal forest types that cover the seasonally dry regions of the tropics.

According to Pennington, although the data are scarce, available figures do suggest tropical savannas play a significant role in the global energy cycle by converting the sun’s energy into organic matter.

“While much more research is needed into ecosystem services, recent studies indicate that tropical savannas account for 30 percent of terrestrial biomass production (net primary production),” he said. “And let’s not forget that some of the most important tropical crops like maize and beans have their origin in tropical dry forests.”

More data is urgently needed, the CIFOR report states, about the severe threats these forests face and the extent to which they are already damaged.

There’s an urgent need for evidence-based policy to support and guide sustainable management of dry forests

Phosiso Sola

Pennington says conversion of dry forest to agriculture is a major threat, with 70 percent of Brazil’s savannas cleared to produce charcoal and for intensive sugar cane, cattle and soya agriculture.

Globally, however, the figures for dry forests are less clear, though they are likely to be just as disturbing. The report finds that “despite general agreement in the (forestry) literature that dry forests are under threat, comprehensive data on the rates of deforestation and conversion of dry forests are difficult to find.” In particular, data is piecemeal for tropical dry forests outside Latin America.

Not enough is known about the value of Africa’s tropical dry forests, says Sola, who sees this lack of knowledge as helping to drive deforestation.

“The value of dry forests is unknown, undocumented and unappreciated; therefore, any other alternative land use is more attractive. Land-use conversion to large-scale agriculture, and large-scale infrastructure development, including urban expansion, are major threats to dry forests,” she said.

DEFINING ‘DRY’

The lack of information about Africa’s loss of tropical dry forests is in sharp contrast to other research about tropical dry forests in the region. According to the CIFOR report, Africa “has by far the greatest body of research on livelihoods, food security, community management and conservation/development trade-offs,” with a significant proportion of this produced by CIFOR.

Deforestation data exists, according to CIFOR, but it does not differentiate between types of forest — and this may be the crux of the whole research problem.Much of the challenge these forests face in getting more research attention is uncertainty about how they are defined.

According to the report, “there is a notable lack of literature that examines dry forests from a global perspective, possibly due to the difficulties in defining what constitutes a dry forest, a topic that has been subject to extensive debate.” CIFOR’s scientists use the term applied by the United Nations Food and Agriculture Organization (FAO), which identifies tropical dry forests as global ecological zones with a “tropical climate, with summer rains … a dry period of 5 to 8 months [and] annual rainfall ranges from 500 to 1500 mm (millimeters).”

So critical is the global adoption of a common standard, the report begins its list of recommendations with a call to establish “an agreed definition of tropical dry forests that CIFOR and related organizations can use to ensure consistency in how the term is used.” The definition proposed by FAO would be “suitable, given its simplicity and broad range,” the report states.

Other recommendations in the report detail gaps in global knowledge about dry forests, analyzing research needs according to themes that include climate change; food security and livelihoods; policies and institutions; energy needs; and sustainable forest management.

Key thematic recommendations include more research into the role that dry forests play in ensuring food security; mitigating climate change through carbon sequestration; and providing wood fuel, charcoal and biofuels. Regional recommendations include calls for more up-to-date information on deforestation in Africa’s dry forests, more livelihoods-based research in Latin America, and more studies across the entire research portfolio in dry forests in Asia, the Pacific and the Caribbean.

Sola said she could not overstate the importance of more and better research into these ecosystems.

“More knowledge about dry forests is essential. There’s an urgent need for evidence-based policy to support and guide sustainable management of dry forests. Millions of poor people could become more vulnerable if the management and use of forests continues in the absence of hard facts and figures.

“The simple truth is that far too much of the data and information needed to underpin sustainable dry forest management is either incomplete or simply doesn’t exist.”